Modular panel frame assembly system

A panel frame assembly system of frame members and member connecting expandable clamps comprising:

• a first at least partially hollow frame member having an open end with opposing planar interior surfaces;
• a second frame member having a pair of adjacent channels having openings extending along at least one side thereof, said second member having a pair of spaced side rails, each having an in turned end flange extending laterally toward the other to define outer edges of the openings of the adjacent channels and a center rail of generally T-shaped configuration to provide a center rail end flange with two free edges defining inner edges of the openings of the adjacent channels, said in turned end flange of each of said side rails and said center rail end flange lying in substantially the same plane;
• and,
• an expandable clamp sized to fit within said first frame member via said open end between said planar interior surfaces and having means for expanding at least portions of said clamp to engage said first frame member so as to prevent removal of the clamp therefrom, said expandable clamp comprising a pair of jaws in relatively moveable relation, each comprising a jaw body having a jaw heat mounted in vertically spaced relation to a jaw neck, said jaw heads being spaced apart from each other a distance greater than the width of said center rail end flange and less than the spacing between said side rail end flanges so as to fit into said channels and said means for expanding being provided as to wedge said jaw heads against said second frame member in said channels inwardly thereof relative said plane.